Spring loaded electrical terminal



Oct. 24, 1967 H DQZ|ER SPRING LOADED ELECTRICAL TERMINAL 2 Sheets-Sheet 1 Filed Aug. 4, 1965 w A I 7 fit: 6

Human B02152,

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United States Patent 3,349,365 SPRING LOADED ELECTRICAL TERMINAL Hilliard Dozier, Cincinnati, Qhio, assignor to U.. Terminals, Inn, Cincinnati, Ohio, a corporation of Ohio Filed Aug. 4, 1965, Ser. No. 477,128 6 Claims. (Cl. 339-254) ABSTRACT OF THE DISCLOSURE A spring loaded electrical terminal comprising a center pin, an insulator, and a displaceable knob member, the parts being preassembled so that the insulator may be inserted in an opening in a terminal board, whereupon the center pin is displaced axially in the direction of the knob member, the knob member being spring biased into clamping engagement with the insulator but displaceable relative to the insulator to expose a central portion of the center pin to which a wire may be detachably secured and clamped in place between the knob and insulator.

This invention relates to electrical terminals and has to do more particularly with a terminal of the so called binding post type wherein the terminal is adapted to detachably receive a wire or connector forming a part of an electrical circuit, the wire being clamped to the terminal by means of a displaceable knob. The instant invention will find particular utility as a loud-speaker terminal or as a terminal for any type of electrical device or test equipment wherein the user is required to connect and disconnect wires from a given terminal.

While variou types of binding posts have hitherto been proposed, they have been cumbersome to handle and difiicult to install in that, as received from the manufac turer', they are composed of a plurality of parts which must be assembled and attached to the terminal board or chassis on which they are mounted. As opposed to the foregoing, the instant invention provides a terminal construction which is completely fabricated by the manufacturer and which, in the hands of the user, merely has to be inserted in an opening in the terminal board or chassis, whereupon by effecting axial movement of the center pin or electrode forming a part of the terminal, the entire structure is securely locked to the terminal board. To this extent, the construction will preferably embody the locking principle set forth in Dozier patent 3,095,470, dated June 25, 1963 and entitled Insulated Electrical Terminal Construction. In accordance with this patent, a terminal composed of an electrode and an insulator is pre-assembled so as to comprise a one-piece unit in the hands of the user, the size of the insulator being such that it may be readily fitted into the opening in a terminal board to which the terminal is to be secured without press fitting, whereupon the electrode is displaced axially with respect to the insulator, the configuration of the electrode acting to expand the insulator so as to effect a positive lock between the terminal and the board.

In accordance with the instant invention, the binding post comprises an electrode or center pin and an insulator, together with a spring loaded knob surrounding one end of the center pin, the spring loaded knob being axially displaceable to expose a portion of the center pin to which a wire or connector may be detachably secured, the spring 3,349,355 Patented Oct, 24, 19%? loaded knob member and the head of the insulator coacting to lock the wire or the like in engagement with the center pin.

A principal object of the invention is the provision of a binding post terminal of the character described wherein the center pin or electrode has a distal portion adapted to be received and wholly contained within a bore in the knob member, the distal portion of the center pin being surrounded by a compression spring arranged to bias the base of the knob member into clamping engagement with the head of the insulator or with a washer overlying the head of the insulator, the base of the knob member and/ or the washer, preferably being of serrated to toothed configuration so as to eifect tight clamping engagement with a wire or other connector attached to the center pin.

A further object of the instant invention is the provision of a binding post terminal construction wherein the distal portion of the center pin has an axial bore therein adapted to receive a test probe, banana plug or phone tip.

Yet another object of the instant invention is the provision of a terminal construction of the character described incorporating locking means effective to temporarily hold the knob member of the terminal in axial displaced condition so as to expose the portion of the center pin to which the wire or other connector is secured.

Further objects of the instant invention which will appear hereinafter or which will be apparent to the skilled worker upon a reading of this specification, are accomplished by that construction and arrangement of parts of which certain exemplary embodiments shall now be described.

Reference is made to the accompanying drawings wherein:

FIGURE 1 is a side elevational view of the center pin or electrode and the insulator used in a binding post terminal constructed in accordance with the instant invention.

FIGURE 2 is a ide elevational view of the center pin and insulator, with the latter in section, illustrating the initially assembled condition of the parts.

FIGURE 3 is a vertical sectional view illustrating the fully assembled terminal prior to its attachment to a terminal board.

FIGURE 4 is a vertical sectional view of the terminal assembly subsequent to its attachment to a terminal board.

FIGURE 5 is a vertical sectional view illustrating the terminal with the knob portion displaced to permit association of a wire or connection with the center pin.

FIGURE 6 is a vertical sectional view illustrating a modification of the invention incorporating means for temporarily maintaining the knob member in displaced position.

FIGURE 7 is a perspective view illustrating the washer member which seats against the head of the insulator and coacts with the undersurface of the knob to clamp the connection to the center pin.

FIGURE 8 is a side elevational View similar to FIG- URE 1 but illustrating a slightly modified electrode having a seat to receive a knob engaging washer.

FIGURE 9 is a vertical sectional view of a fully assembled terminal having a knob which is adapted to be locked in elevated position upon engagement with the lugs of the washer.

FIGURE 10 is a top plan view of the knob and washer.

FIGURE 11 is a vertical sectional view similar to FIGURE 8 but showing the knob locked in the elevated position.

Referring first to FIGURE 1, the electrode or center pin is indicated generally at 1, the pin being formed from a conductive metal and machined to provide a central body portion 2 which preferably will have a cross-drilled opening 3 therein for receiving the wire or connector to be detachably secured thereto; although the wire may be wrapped around the body of the pin if so desired. A bore engaging shoulder or barb 4 underlies the central body portion 2 and lies in spaced relation to an expansion shoulder 5 which terminates in an enlarged milled or knurled expansion part 6 which lies adjacent the annular cap 7. An extension 8 projects outwardly beyond the cap 7, to which a wire or connector is adapted to be fixedly secured, as by soldering,-the extension preferably having a cross-drilled opening 9 through which the wire is passed. At the opposite end of the center pin a distal portion 10 projects upwardly from the central body portion 2, the distal portion having a probe receiving bore 11 extending inwardly from its free end.

The insulator 12;, which is formed from a relatively hard yet distortable material, such as Teflon or other comparable dielectric material, has a cylindrical body portion 13 terminating at one end in a beveled edge 14 and at its opposite end in an enlarged head 15. The insulator has an axial bore 16 which, as will become apparent hereinafter, is of a size to permit the distal portion 10 and body portion 2 of the center pin to be passed therethrough so as to bring the parts to the condition illustrated in FIG- URE 2, which comprises the initial state in the assembly of the terminal structure.

A washer 17 is preferably fitted over the distal end of the center pin and is pressed downwardly over the central body portion 2 where it makes binding contact with the center pin. As seen in FIGURE 6-, the washer 17 is provided with a plurality of oppositely directed prongs 18 which provide tooth-like projections extending both upwardly and downwardly. If desired, the face of the enlarged head of the insulator may be serrated or toothed, although it will usually be smooth.

A knob member 19 having a central bore 20 is adapted to be fitted over the distal portion 10 of the center pin, the knob member preferably having serrations or teeth 21 on its lowermost end which seats against the washer 17 or the head of insulator, depending upon whether a washer is used. The knob member normally will have an enlarged gripping portion 22 by means of which it may be conveniently gripped by the user; and the knob will be formed from plastic or other suitable dielectric material. The bore 20 has an internal shoulder 23 against which the lowermost end of a compression spring 24 is seated, the compression spring surrounding the distal portion 10 of the center pin. A washer 25 contacts the opposite ends of the spring which is held in compressed position by flaring the free end of the distal portion 10 outwardly over the washer, as indicated at 26. The spring thus serves to attach the knob member 19 to the center pin and at the same time urges its lowermost end into clamping engagement with the underlying washer 17. This is the factory assembled condition of the terminal in which it is shipped to the user.

In the hands of the user, the terminal assembly has merely to be inserted in an opening in a terminal board of a size to just nicely receive the cylindrical body portion 13 of the insulator with the enlarged head of the insulator seated against one surface of the terminal board. Such a terminal board is indicated in dotted lines at 27 in FIGURE 3. Once the insulator has been inserted in the terminal board and the head seated thereagainst, a support or other holding means, indicated by the arrows A in FIGURE 4, is placed against the outermost face of the knob member 19, whereupon the center pin is displaced axially in the direction of the arrow B, thereby forcing the expansion shoulder 5 and enlarged body part 6 into the cylindrical body portion 13 of the insulator, with the cap 7 seated against the end of the insulator.

The dimensioning of the parts is such that the cylindrical body portion of the insulator will be expanded radially outwardly, as indicated at 1311, and the terminal thus permanently locked in place by the bulging body portion 13a which lies immediately beyond the surface of the terminal board 27. The cap 7 serves to establish the final position of the center pin relative to the insulator and also keeps the insulator in axial compression, and in such final position the major portion at least of the milled or knurled body part 6 lies beyond the surface of the terminal board on the side opposite the enlarged head 15. The knurled body part 6 bites into the insulator and prevents rotation of the center pin relative to the insulator, as does the toothed washer; and in similar fashion the barb 4 bites into the insulator to prevent withdrawal of the center pin.

When it is desired to insert a wire or other conductor in the opening 3, the knob member 19 is displaced in the manner illustrated in FIGURE 5, thereby exposing the ope ling 3 so that the wire or conductor may be passed therethrough, or a wire wrapped around the center pin, whoreupon the knob member is released and under the infl lence of the spring 24 is pressed downwardly into clamping engagement with the wire. It will be readily app arent that should it be desired to disconnect the wire 3116, possibly, insert a different one, the user merely has to raise the knob member, remove the wire to be disconnet ted and insert the one to be connected, whereupon the knob is released for return to the clamping position under the influence of spring 24.

FIGURE 6 illustrates a modification of the invention wherein means are provided to maintain the knob member in its elevated or displaced position. To this end, the center pin is provided with an annular ledge 28 cut inwardly from the periphery of the center pin, which ledge is adapted to serve as a stop for a portion of an annular abutment 29 formed on the undersurface of the knob 19. As will be evident from FIGURE 6', if the knob is tilted slightly from the axis of the center pin while in the elevated position and then released, one side of the abutment 29 will engage the annular ledge 28, thereby retaining the knob in the elevated position against the compression of spring 24. The knob may be readily released by simply displacing it laterally in a direction which will disengage the abutment 29.

FIGURE 8 illustrates another modification wherein the electrode 1a differs from the electrode shown in FIG- URE 1 in that the distal portion 10 is provided with an annular shoulder or seat 30 on which a washer 31, which is possibly best seen in FIGURE 10, is adapted to be seated, the washer having spaced apart, outwardly projecting lugs 32 adapted to be received in vertically disposed channels 33 formed in the knob member 19. The washer is held in place by flaring the free end of distal portion 10 outwardly over the washer, as indicated at 26, thereby effectively securing the washer against the seat 30. The washer 31 is thus prevented from moving axially along the distal portion 10 of the electrode.

When in its normal position of use, the terminal assumes the condition illustrated in FIGURE 9 wherein it will be seen that the distal end of the electrode projects upwardly toward the uppermost edge of the central bore 20 in the knob member, with the lugs 32 of the washer lying within the vertically disposed channels 33. When the knob member 19 is displaced upwardly to expose the opening 3 in the electrode, the lugs of the washer are brought into alignment with an annular recess 34 surrounding the central bore 20 in the knob member and, when the lugs are in alignment with the recess, rotation of the knob will cause the lugs to enter the portions of the recess lying intermediate the vertical channels. Upon release of the knob member with the lugs displaced from the vertical channels so as to lie within the confines of the annular recess, the lugs will engage the uppermost wall surface of the annular channel and hence the knob member will be effectively locked in its elevated or displaced position, the parts thus assuming the condition illustrated in FIGURE 11. The opening 3 is thus exposed for the insertion of a wire or connector. Once the desired connection has been made, the knob member will be rotated until the lugs are again brought into alignment with the vertically disposed channels 33, whereupon the knob is free to move downwardly into clamping engagement with the wire under the influence of the spring 34, While a preference is expressed for washer having three equally spaced apart lugs projecting outwardly from its circumference, it will be understood that the number of lugs may be varied to suit the conditions of use.

Modifications may be made in the invention without departing from its spirit and purpose. Several modifications have already been given and others will undoubtedly occur to the worker in the art upon reading this specification; and consequently it is not intended that the invention be limited other than in the manner set forth in the claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A spring loaded electrical terminal comprising a center pin, an insulator, and a displaceable knob member, said center pin comprising an elongated electrode having a central body portion for receiving a wire to be detachably connected to said terminal, said central body portion terminating at one end in an elongated distal portion and at its opposite end in an extension for attaching a second wire to said terminal, said center pin being surrounded by said insulator in an area intermediate said central body portion and said extension, said insulator acting as a means for securing said terminal to a supporting surface; said displaceable knob member comprising a body having a base end and a top end, a central bore extending through said body from one end to the other, said central bore having an inwardly directed shoulder adjacent the base end of said body, said knob member being fitted over the distal portion of said center pin with the base of said knob member facing said insulator, said insulator having a knob supporting surface facing the base of said knob member, a compression spring surrounding the distal portion of said center pin with the innermost end of said spring seated against said inwardly directed shoulder, the opposite end of said spring being operatively connected to said center pin, said spring being in compressed condition whereby to urge the knob member in the direction of the knob supporting surface of said insulator so as to enter into clamping engagement with a wire attached to the central body portion of said center pin, an annular ledge cut inwardly from the periphery of said center pin, and a coacting annular abutment on the base end of said knob member, said annular ledge and abutment coacting when engaged to maintain said knob member in a displaced position in which the central body portion of said center pin is exposed for the attachment of a wire thereto.

2. A spring loaded electrical terminal comprising a center pin, an insulator, and a displaceable knob member, said insulator being formed from a distortable dielectric material and having a cylindrical insulator body portion terminating at one end in an enlarged insulator head, and an axial insulator bore extending entirely therethrough; said center pin comprising an elongated electrode having a central body portion for receiving a wire to be detachably connected to said terminal, said central body portion terminating at one end in an elongated distal portion and at its opposite end in an extension for attaching a second wire to said terminal, said center pin also having a barbed shoulder intermediate said central body portion and said extension, and enlarged expansion part positioned outwardly beyond said barbed shoulder, and a cap beyond said expansion part, said cap being of a larger diameter than said insulator bore, said center pin being inserted in the axial bore in said insulator from the end thereof op posite the enlarged insulator head and movable from a preassembled position in which the central body portion of said pin lies within said insulator bore in the area of said enlarged insulator head, said barbed shoulder is in engagement with said insulator bore in the area of said insulator body, and said expansion part lies outwardly beyond the end of said insulator body, to a fully assembled position in which the said central body portion of said pin projects outwardly beyond said insulator head, said barbed shoulder is in engagement with said insulator bore in the area of said insulator head, and said expansion part is contained within said insulator bore with said cap seated against the end of said insulator; said displaceable knob member comprising a knob body having a base end and a top end and a central knob bore extending through said knob body from one end to the other, said central knob body having an inwardly directed shoulder adjacent the base end of said knob member, said knob member being fitted over the distal portion of said center pin with the base end of said knob member facing the enlarged head of said insulator, a compression spring surrounding the distal portion of said center pin with the innermost end of said spring seated against said inturned shoulder, the opposite end of said spring being operatively connected to the free end of the distal portion of said center pin, the combined lengths of the central and distal portions of said center pin being less than the length of said knob bore, the length of said spring being such that it will be under compression both when said center pin is in its preassembled and fully assembled positions, whereby the base end of said knob member will be urged into clamping engagement with the head of said insulator at all times and will surround and cover the central portion of said pin when said pin is in the fully assembled position, but said knob may be raised against the further compression of said spring to expose the central portion of said pin for the attachment of a wire thereto.

3. The terminal construction claimed in claim 2 wherein said center pin and said knob member include coacting means for maintaining said knob member in a raised position when said pin is in its fully assembled position.

4. The terminal construction claimed in claim 3 wherein the coacting means for maintaining said knob in its raised position comprises a Washer surrounding the distal end of said center pin, said washer having at least one outwardly projecting lug, said knob member having a vertically disposed channel projecting outwardly from said knob bore in which said lug is received, and an annular recess extending peripherally around said knob bore and positioned to receive said lug when said knob member is displaced axially with respect to said center pin and, upon alignment of said lug with said annular recess, said knob member is rotated to cause said lug to enter said annular recess.

5. The terminal construction claimed in claim 4 wherein the coacting means for maintaining said knob member in raised position comprises an annular ledge cut inwardly from the periphery of said center pin and a coacting annular abutment on the base end of said knob member.

6. The terminal construction claimed in claim 2 wherein the central body portion of said center pin is of larger diameter than its distal portion, the said central body portion and distal portion being joined by a shoulder, wherein said shoulder coincides with the outer surface of the enlarged head of the insulator when said center pin is in its preassembled position, and wherein a washer surrounds said center pin and is seated against said shoulder when said center pin is in its preassembled condition, said washer having an inside diameter which will make binding contact with said central body portion when said center pin is in its fully assembled position, said washer having serrations adapted to enter into biting engagement with a wire attached to said central body portion and with the enlarged insulator head.

(References on following page) 7 8 References Cited 2,921,286 1/1960 Gordon 17S153 X 2,948,773 8/1960 Hawes 174-453 X UNITED STATES PATENTS 3,095,470 6/1963 Dozier 174 1s3 1,245,628 11/1917 Smith 339 254 1,694,239 12/1928 Thonsen 339-254 X 5 FOREIGN PATENTS 1,697,954 1/1929 Gribbie 339 277 491,346 3/1953 Canada- 1,746,639 2/1930 Dunzweiler 339 254 X 1,024,602 2/1958 Germany- 1,825,130 9/1931 Schneider 339 254 X- 2,349,097 5/1944 Kenneuy X- MARVINA. CHAMPION, Plzmary Exammel.

2,701,871 2/1955 Rauch 339 254 10 P. TEITELBAUM, Assistant Examiner. 

1. A SPRING LOADED ELECTRICAL TERMINAL COMPRISING A CENTER PIN, AN INSULATOR, AND A DISPLACEABLE KNOB MEMBER, SAID CENTER PIN COMPRISING AN ELONGATED ELECTRODE HAVING A CENTRAL BODY PORTION FOR RECEIVING A WIRE TO BE DETACHABLY CONNECTED TO SAID TERMINAL, SAID CENTRAL BODY PORTION TERMINATING AT ONE END IN AN ELONGATED DISTAL PORTION AND AT ITS OPPOSITE END IN AN EXTENSION FOR ATTACHING A SECOND WIRE TO SAID TERMINAL, SAID CENTER PIN BEING SURROUNDED BY SAID INSULATOR IN AN AREA INTERMEDIATE SAID CENTRAL BODY PORTION AND SAID EXTENSION, SAID INSULATOR ACTING AS MEANS FOR SECURING SAID TERMINAL TO A SUPPORTING ING SURFACE; SAID DISPLACEABLE KNOB MEMBER COMPRISING A BODY HAVING A BASE END AND TOP END, A CENTRAL BORE EX TENDING THROUGH SAID BODY FROM ONE END TO THE OTHER, SAID CENTRAL BORE HAVING AN INWARDLY DIRECTED SHOULDER ADJACENT THE BASE END OF SAID BODY, SAID KNOB MEMBER BEING FITTED OVER THE DISTAL PORTION OF SAID CENTER PIN WITH THE BASE OF SAID KNOB SUPPORTING SURFACE FACING THE BASE SULATOR HAVING A KNOB SUPPORTING SURFACE FACING THE BASE OF SAID KNOB MEMBER, A COMPRESSION SPRING SURROUNDING THE DISTAL PORTION OF SAID CENTER PIN WITH THE INNERMOST END OF SAID SPRING SEATED AGAINST SAID INWARDLY DIRECTED SHOULDER, THE OPPOSITE END OF SAID SPRING BEING OPERATIVELY CONNECTED TO SAID CENTER PIN, SAID SPRING BEING IN COMPRESSED CONDITION WHEREBY TO URGE THE KNOB MEMBER IN THE DIRECTION OF THE KNOB SUPPORTING SURFACE OF SAID INSULATOR SO AS TO ENTER INTO CLAMPING ENGAGEMENT WITH A WITE ATTACHED TO THE CENTRAL BODY PORTION OF SAID CENTER PIN, AN ANNULAR LEDGE CUT INWARDLY FROM THE PERIPHERY OF SAID CENTER PIN, AND A COACTING ANNULAR ABUTMENT ON THE BASE END OF SAID KNOB MEMBER, SAID ANNULAR LEDGE AND ABUTMENT COACTING WHEN ENGAGED TO MAINTAIN SAID KNOB MEMBER IN A DISPLACED POSITION IN WHICH THE CENTRAL BODY PORTION OF SAID CENTER PIN IS EXPOSED FOR THE ATTACHMENT OF A WIRE THERETO. 